1. Field of the Invention
This invention relates to the preparation of noncellular polyurethane elastomers. It is particularly concerned with the use of trimerization catalysts and organo-mercury compounds as co-catalysts in the preparation of noncellular polyurethane elastomers.
2. Description of the Prior Art
It is known to prepare polyurethane elastomers by the reaction of an organic polyisocyanate with an organic compound containing at least two active hydrogens as determined by the well-known Zerewitinoff method. In order to prepare noncellular polyurethane elastomers, the reaction is carried out in the presence of a delayed reaction catalyst in the absence of a blowing agent. Typical delayed reaction catalysts are organo-mercury compounds such as those described in U.S. Pat. Nos. 3,583,945; 3,927,053; 2,692,204; and 3,642,044. Delayed reaction catalysts are used because it is known that any water in the system (any system will have some water in it even though none is added) will react with the organic polyisocyanate and cause the formation of carbon dioxide. Therefore, this reaction must be minimized if a noncellular elastomer is wanted.